Forecast Discussions mentioning any of "HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 09/12/20

Area Forecast Discussion...UPDATED
National Weather Service Albuquerque NM
552 PM MDT Fri Sep 11 2020 .AVIATION... 00Z TAF CYCLE VFR conditions are expected for the next 24 hours. High altitude smoke will continue to cross the southern half of the forecast area. Winds should be less gusty on Saturday than they were today. 44 && .PREV DISCUSSION...254 PM MDT Fri Sep 11 2020... .SYNOPSIS... Temperatures will continue to trend warmer into the weekend. Upper level smoke will drift into the Land of Enchantment from the west, remaining mostly aloft. Dry and clear conditions will prevail next week. The exception will be some spotty showers and thunderstorms across the southwest and south central mountains each day through Tuesday. Temperatures will continue to trend up through the end of the week, as upper level high pressure elongates in the Desert Southwest. && .DISCUSSION... SHORT TERM...(TONIGHT THROUGH SATURDAY)... Deep layer, dry westerly flow over NM has mixed to the surface with lcl breezes at several locales, especially eastern NM. Temps have trended much warmer today with only a few thin cirrus and some cu near the high terrain. A thick veil of upper level smoke has shifted into the southern half of NM from massive wildfires burning over CA. The 12Z-18Z HRRR smoke guidance shows this smoke remaining aloft, however high level smoke will make for brownish skies with haze increasing over the region. Flow aloft will veer west to northwest Saturday as a strong upper level ridge slides east from the Great Basin. This will force most of the smoke into southern NM Saturday. Temps will trend warmer again Saturday but still remain 5 to 10F below normal. A weak northeast wind shift will slide into eastern NM as surface high pressure builds down the Front Range. No impacts to sensible weather are expected with the boundary other than a few more afternoon cu. LONG TERM...(SUNDAY THROUGH FRIDAY)... High pressure in the Great Basin meanders east on Sunday, as energy from the base of longwave trough across the Great Plains breaks off to form a low over northern NM. This setup will create a Rex block, which will allow dry air to prevail over the majority of the CWA, while modest moisture near the low increases precip potential. While the return flow remains meager, daily showers and thunderstorms are possible each afternoon through Tuesday across the southwest and south central mts. By midweek, the upper high will push east, overtaking the low, and becoming the dominant feature through the rest of the week. Temperatures will trend up, as dry and clear conditions prevail into the weekend. Guyer/12 && .FIRE WEATHER... Dry westerly flow over NM has trended temps warmer with lower RH and local breezy winds today. Thick smoke aloft from CA will stream over NM thru Saturday before shifting southward Sunday. A weak upper level wave will develop over the region this weekend and drift southwest thru next week. There is little moisture to work with so mostly afternoon clouds are expected near the mountains and perhaps an isolated shower each day. Light winds and weaker m Guyer && .ABQ WATCHES/WARNINGS/ADVISORIES... None. && $$
Area Forecast Discussion
National Weather Service La Crosse WI
1030 PM CDT Fri Sep 11 2020 .SHORT TERM...(This evening through Saturday) Issued at 210 PM CDT Fri Sep 11 2020 Main forecast focus is on the rain/storms into Saturday. Water vapor imagery as of early afternoon shows a deep closed upper low across the central high plains with a plume of moisture advecting north ahead of the trough into the Upper MS Valley. Isentropic ascent/moisture transport will ramp up through the late afternoon and evening with showers becoming more widespread and spreading north and east through late day as a weak embedded shortwave trough lifts across the area. Precipitable water values will increase to around 1.75 inches this evening with a deep warm cloud layer. A limiting factor for heavy rainfall amounts will be the weak instability, with MUCAPE of only a few hundred J/kg. As a result, expect mainly periods of showers tonight with embedded storms. Rain amounts of generally 1/2 to an 1.5 inches are expected from northeast IA through central WI , with isolated amounts of 2+ inches possible mainly over northeast IA and far southwest WI, and lower amounts farther west across parts of southeast MN. Do not anticipate much of a flash flood threat, but some rises on rivers and streams are possible. Temps overnight tonight should remain fairly steady with persistent warm advection. Precip will diminish Saturday morning as the slug of isentropic ascent/moisture transport pushes off to the east. A few additional showers through the afternoon are possible as the upper low approaches. Highs on Saturday are expected to be in the 60s for much of the area. .LONG TERM...(Saturday night through Friday) Issued at 210 PM CDT Fri Sep 11 2020 As the upper level shortwave moves east through the area on Saturday evening, scattered showers will be seen across the area. There will be very little additional rain from these showers. Tuesday continues to look like it will be rather windy. 950 to 900 mb lapse rates will climb to around 9C/km ahead of an approaching surface front and shortwave trough. This wind signal has been very consistent signal among the ECMWF ensemble members for the past 3 to 4 days. They continue to suggest wind gusts of 25 to 40 knots. The GFS model soundings also suggest similar wind gusts. The NBM looks too low with its wind gusts so raised them by 5 knots which will put most areas in the 25 to 35 knot range. From Thursday and beyond, the models diverge on the strength of a trough moving through the area. The ECMWF is much deeper with this system, so temperatures are much cooler than the GFS and the operational ECMWF is supported by its ensemble mean. However, with this said, there is quite a bit of spread among its members, so confidence is rather low for this time period. && .AVIATION...(For the 06Z TAFS through 06Z Saturday night) Issued at 1030 PM CDT Fri Sep 11 2020 Cigs: mostly IFR/LIFR cigs through tomorrow morning as an upper level trough slowly tracks east across the region this weekend. Should see improvement Sat afternoon, post cold frontal passage. Could bump into VFR for a short period Sat evening, but not anticipating clearing until Sun when the trough axis swings east. WX/vsby: -dz/shra through the night, shifting east Sat morning. Expect vsby restrictions into Sat morning. Should get a break, but cold air a loft coupled with favorable low level lapse rates could spark sct/isold -shra for the afternoon. Latest meso models not as enthusiastic as earlier runs - so opting to remove vcsh. Meanwhile, can`t rule out some isold thunder chances overnight - RAP bufkit soundings hint at meager instability aloft. Not confident enough to mention in forecast for the moment, but will adjust if threat increases. Winds: east/southeast through the overnight, swinging to the west by late morning/early afternoon Sat with passage of a cold front. Low level jet streaks across KLSE overnight, and could result in a short period of LLWS for KLSE. However, latest RAP trending away from stronger winds. Will hold onto LLWS for the moment and monitor. Positioning of jet limits LLWS concerns at KRST. && .ARX WATCHES/WARNINGS/ADVISORIES... WI...None. MN...None. IA...None. && $$ SHORT TERM...JM LONG TERM...Boyne AVIATION...Rieck
Area Forecast Discussion
National Weather Service Bismarck ND
1020 PM CDT Fri Sep 11 2020 .UPDATE... Issued at 1020 PM CDT Fri Sep 11 2020 Shower activity has greatly diminished over the last hour or two, a trend which has been supported by the 00Z suite of model guidance. Therefore, we have limited PoPs at 30 percent, which still may be too high. Otherwise, recent high-resolution models have trended toward fog developing across portions of central North Dakota. Both radiational fog and advection fog would seem possible given breaks in cloud cover and southeast surface flow, so we have added a patchy fog mention to the forecast through mid morning. UPDATE Issued at 713 PM CDT Fri Sep 11 2020 Shower activity has slowly increased in areal coverage across southern North Dakota, and now extends as far west as the Montana border. High resolution models are doing an okay job of depicting this scenario, with the NAMNest, ARW, and NMM performing better than the HRRR and RAP. PoPs were updated through the night to reflect these trends. Sky cover was also greatly increased based on observed trends and pattern recognition. Some patchy fog may need to be added to south central and southeast North Dakota, but will wait to see how the situation evolves. This potential fog would mostly be driven by low level moisture advection. && .SHORT TERM...(This evening through Saturday) Issued at 141 PM CDT Fri Sep 11 2020 The closed low that is spinning across the Nebraska Panhandle will slowly drift northeast overnight tonight. As it does it will advect in some low/mid-level moisture. Some scattered light showers are possible across south central ND and the James River Valley this afternoon through overnight. However, dry air entrainment and weak forcing could limit chances/coverage of precipitation tonight. Saturday, the upper-level low moves out and northwesterly flow aloft moves in. We`ll see much warmer temperatures than today as an 850 mb warm nose moves in and mixes down with modestly steep lapse rates. Saturday should be dry as we`ll be in a lull between two systems. A cold front approaches Saturday night. .LONG TERM...(Saturday night through Friday) Issued at 141 PM CDT Fri Sep 11 2020 A weak cold front will slide through late Saturday night and Sunday morning. Very little moisture and weak upper-level support means the majority of the area will be dry. Some slight chances of precip are possible across the far northeast (closer to the upper-level support). Upper-level ridging moves in early next week. Above average temperatures are expected as a result. By midweek a cold front will bring the next chance for showers and a cooldown Tuesday or Wednesday depending on which model solution verifies (GFS Tues. vs ECMWF Wed.) && .AVIATION...(For the 00Z TAFS through 00Z Saturday evening) Issued at 713 PM CDT Fri Sep 11 2020 Ceilings are forecast to lower to MVFR/IFR levels at KBIS and KJMS this evening, lasting through the night. Scattered showers are also possible at these sites. Upstream observations indicate that some lower visibilities due to drizzle or fog may be possible at KBIS and KJMS overnight, but confidence is not high enough to mention this in the TAF at this time. Elsewhere, ceilings are expected to remain at VFR levels, with conditions becoming VFR at all terminals by Saturday afternoon. Southerly winds this evening will slowly turn northwesterly on Saturday, generally remaining under 10 kts. && .BIS WATCHES/WARNINGS/ADVISORIES... NONE. && $$ UPDATE...Hollan SHORT TERM...AJ LONG TERM...AJ AVIATION...Hollan
Area Forecast Discussion...UPDATED
National Weather Service Hanford CA
333 PM PDT Fri Sep 11 2020 .UPDATE...Updated AIR QUALITY ISSUES section. && .SYNOPSIS...Areas of dense smoke from regional fires will continue to impact the area, lowering afternoon high temperatures with continued poor air quality. Temperatures will increase into the middle of next week as a ridge moves into the area. Dry weather will continue to prevail for at least the next 7 days. && .DISCUSSION...Yet another very smokey day across the central California interior as the SQF and Creek fires continue to burn in the Sierra Nevada. The heavy smoke generated by these fires (along with the others in the Western U.S.) has kept today`s temperatures to around 80 to 85 degrees in the valley, desert, and foothill locations. These temperatures are up to 10 degrees below normal, which is a far cry from the oppressive heat we experienced last week. The heavy smoke has also help lower any extreme fire activity today. So there are some benefits to the smokey conditions in the region, positive thinking! The HRRR smoke model output continues to show very heavy smoke across the region tonight through tomorrow evening. This solution does make sense given the continued light low and upper level winds across the region. Current thinking is that the dense smoke will not disperse much if at all tomorrow which will keep our high temperatures similar to today. For the extended period, deterministic and ensemble model output all indicate that a ridge of high pressure will continue to move into the Four Corners region. This ridge then strengthens through the middle of next week. Temperatures are expected to increase back to normal to slightly above normal readings during this period. The aforementioned ridge will continue to move east into the central plains by the end of next week, as a deep trough moves into the Pacific Northwest. Synoptic cooling and increased onshore flow will lower temperatures to as much as 10 degrees below average by the end of next week. At this time, no precipitation is expected across the region for the foreseeable future. && .AVIATION... Mainly MVFR visibility in the San Joaquin Valley and IFR visibility in the Sierra Nevada and adjacent foothills during the next 24 hours due to smoke from wildfires in the Sierra Nevada. Elsewhere, VFR conditions will prevail over the central CA interior for the next 24 hours. && .AIR QUALITY ISSUES... Please see SFOAQAHNX for an Air Quality Alert On Saturday September 12 2020...Unhealthy in Fresno...Madera and Merced Counties and Sequoia National Park and Forest. Unhealthy for sensitive groups in Kern...Kings and Tulare Counties. Further information is available at && CERTAINTY... The level of certainty for days 1 and 2 is medium. The level of certainty for days 3 through 7 is medium. Certainty levels include low...medium...and high. Please visit for additional information an/or to provide feedback. && .CERTAINTY... The level of certainty for days 1 and 2 is medium. The level of certainty for days 3 through 7 is medium. Certainty levels include low...medium...and high. Please visit for additional information an/or to provide feedback. && .HNX WATCHES/WARNINGS/ADVISORIES... None. && $$ Public/Avn/Fire Wx.....CMC IDSS/PIO...............Mattarochia
Area Forecast Discussion
National Weather Service Jackson MS
927 PM CDT Fri Sep 11 2020 .UPDATE... Updated for evening discussion. && .DISCUSSION... Ongoing unsettled airmass across the region keeping some convection going into the evening hours. Have made a few minor updates for some showers in the north and southeast to continue as the overall weakening trend continues. Some minor adjustments to the hourly trends and to expand cloud cover, but overall no major updates anticipated at this time. Prior discussion below: Tonight and Saturday: Continued warmer than normal through the period with greater rain chances. Mid afternoon satellite imagery showed flow around an inverted trough extending north from the northern Gulf over our northeast Louisiana Parishes. This feature will continue shifting east tonight and bring an increase in tropical moisture back across our whole CWA from the southeast by Saturday morning. Satellite derived PWAT was showing around 2.1in over much of our CWA; up from 1.72in off the morning JAN sounding. Daytime heating of this moist airmass was leading to the development of scattered showers and thunderstorms, generally southeast of the Natchez Trace. This activity will continue spreading west into this evening before dissipating. Wl not carry pops past midnight and a very humid night is on tap. Surface dew points were running in the low to mid 70s this afternoon and wl continue tonight leading to morning lows in the low to mid 70s. Normal lows run in the mid 60s at most locations. Saturday the mid level high centered to our east that has been dominant will continue to weaken as the closed low spinning over the Plains edges closer to our CWA. The moist tropical airmass combined with lower heights and daytime heating should lead to a greater coverage of mainly afternoon showers and thunderstorms than today. Greatest coverage of storms will be across our southeast. The clouds and rain will hold more locations to the upper 80s but most sites are expected to top out again in the lower 90s. Normal highs this time of the year run in the upper 80s. /22/ Saturday night through Next Week... Deep troughing continues over the western half of the CONUS which results in a continued sub-tropical ridge over the ArkLaMiss region through at least Saturday. To kick things off, the deep trough over the west will slide across the midwest Saturday, combined with moisture from the Gulf, this will help with increased rain chances Saturday and Sunday. By Sunday, the previously mentioned trough will flatten out and stretch across the north, dropping a weak cold front across which will be another aid in helping diurnal activity across the ArkLaMiss Sunday and Monday. There may be potential for some quick heavy down pours ahead of the front Sunday. Dewpoints will increase into the mid-upper 70s(74-76F) meaning there will be efficient moisture to support some possible heavy rainfall. Low temperatures will be in the lower 70s Saturday night and high temperatures Sunday will be in the upper 80s from the upper 80s areawide. As far as the next working week goes, models have came into better agreement with some synoptic features. Both the GFS and ECMWF display a ridge building back over the northwest CONUS and troughing across the midwest/eastern areas Monday. For us here in the Deep South, our main concern will be thunderstorms due to an organized area of low pressure just off the coast of the Bahamas. It is possible within the next 24-48 hours or so that it develops into a Tropical depression. Regardless, afternoon through early evening thunderstorms and locally heavy rainfall will be the case for our region Sunday through at least Thursday. We will continue to monitor activity in the Gulf and as always keep you updated with the latest./JNE/ && .AVIATION... 00Z TAF discussion: Decaying convection will keep some vcsh in for the first couple of hours of the forecast. Generally a VFR TAF with the exception of HBG/PIB/MEI with the development of IFR stratus near dawn. Given the areal scope of the precip this afternoon/evening...expect that that northern edge of the low stratus may stretch back far enough to the NW to clip JAN/GTR. HRRR at this point comes close... but only briefly. Will maintain the more optimistic forecast and keep an eye on overall trends. && .PRELIMINARY POINT TEMPS/POPS... Jackson 74 90 74 89 / 19 68 32 71 Meridian 74 90 73 89 / 22 71 27 62 Vicksburg 74 92 74 89 / 22 64 32 65 Hattiesburg 74 90 72 90 / 25 76 25 64 Natchez 73 90 73 89 / 37 68 28 67 Greenville 74 91 73 88 / 21 58 33 60 Greenwood 74 92 73 88 / 18 64 40 69 && .JAN WATCHES/WARNINGS/ADVISORIES... MS...None. LA...None. AR...None. && $$ HJS
Area Forecast Discussion
National Weather Service Elko NV
212 PM PDT Fri Sep 11 2020 .SYNOPSIS...Warm and dry conditions will remain through early next week and high pressure builds across the region. Daytime highs could reach into the low 90s through the weekend. Haze and smoke may return to northern and central Nevada late Friday into Saturday morning. && .SHORT TERM...Today through Sunday evening. Although GOES imagery highlights clear skies across much of Nevada, smoke from CA/OR fires is lurking at the horizon waiting for a favorable shift in the upper air flow before progressing once again over northern NV. That chance could come during the early morning hours Saturday as HiRes model guidance and HRRR simulations hint at upper winds shifting just enough through the 24-36 hrs to pull smoke from fires over northern CA and western OR into northern NV by tomorrow morning. Uncertainty is quite high as to the exact timing and spacial extent of the smoke layers since it depends upon how fast the upper high re-centers itself over the forecast area through Saturday evening. But what is certain is that above average temperatures and dry conditions will move back into northern NV through the weekend. Some central NV locations could see some afternoon wind gusts topping 20kts that will only contribute to an elevated fire weather concern. High temperatures will be largely in the 80s but some interior locations could see thermometers topping in the low 90s. Low temperatures will generally be in the 40s to low 50s into next week. .LONG TERM...Sunday evening through next Friday. Relatively stable long wave pattern with warm ridge positioned over the Four Corner states. Pacific trough appears to be in no hurry on moving onshore, but does place Nevada under southwest flow aloft. This wind direction may bring smoke and haze from California wildfires into our region, particularly Humboldt County. Wind may increase with some gusts to 30 mph across northern Nevada as a short wave ejects into the Pacific Northwest on Monday. The latest operational GFS and EC are in reasonable agreement that the Pacific trough will be over Nevada by Friday. Not so fast per the ensemble cluster analysis, where 3 of the 4 clusters keep the trough along the California coast or over the eastern Pacific by next Friday. NBM guidance shows a slow cooling trend next week from near 90 on Monday to the lower to mid 80s on Friday. Nearly bone dry with respect to any rainfall, maybe a shower over the northern mountains (north of I-80) next Friday. && .AVIATION...VFR conditions are expected at KWMC KBAM KEKO KELY and KTPH through Saturday. Smoke layers from wildfires could gradually advance east and southeast over parts of northern NV Saturday morning. There is a risk for MVFR conditions at KWMC and KBAM as the smoke thickens later in the forecast period. && .FIRE WEATHER...No real changes in the general warming and continued dry conditions across the region through early next week. Although relative humidity values will sink back into the single digits with afternoon wind gusts approaching 20 kts across parts of northern and east central Nevada, the region will for the most part remain below critical criteria into early next week. && .LKN WATCHES/WARNINGS/ADVISORIES... None. && $$ 97/88/97/97
Area Forecast Discussion...UPDATED
National Weather Service Los Angeles/Oxnard CA
647 PM PDT Fri Sep 11 2020 .SYNOPSIS...11/325 AM. Night through morning low clouds and fog will affect coastal areas through the middle of next week. Otherwise, mostly clear skies with smoke layers at times will persist through the period. Temperatures will generally be near to above normal through the middle of next week. However, high temperatures will be dependent upon day to day fluctuations on the density of smoke through the atmosphere. && .SHORT TERM (TDY-MON)...11/250 PM. After inspection of local webcams and fog product satellite pictures, it was decided to extend the dense fog advisory until 11 am this morning. Otherwise, the forecast is in good shape with today`s highs lowered some because of sunlight attenuation due to the thick layer of smoke. A quick look at the HRRR integrated smoke loop shows a steady supply of smoke into the night time hours tonight. Low temperatures this morning were surprisingly low in a few zones, so we may need to adjust tonight`s low temperatures downward a touch. The smoke may be a bit thinner this morning, as the sun appears as a 200 watt bulb in contrast to the 100 watt bulb we saw in the sky yesterday. We will have to monitor the smoke closely, in case the HRRR smoke model deviates from reality. The high temperatures for tomorrow are forecast to be warmer in most locations, but continued presence of a thick smoke layer may necessitate a slight downward adjustment. Early projections from the morning model data are showing a better presence of marine clouds along the coast, probably a result of the projected increase in onshore gradients for the upcoming weekend. It is entirely possible that we will see another round of dense fog in some coastal sections tonight. So far, afternoon temperatures for today are working out rather well, and they seem to be a good guide for the highs tomorrow. The smoke is expected to hang around through tomorrow, but the slight thinning today did help temperatures south of Point Conception warm up about 5 degrees. Satellite pictures are showing another reinforcing shot of smoke dropping into areas south of Point Conception at this time. If the sun is capable of producing shadows again tomorrow, the temperatures for tomorrow will be about right. If we go back to a 100 watt bulb in the sky tomorrow with no shadows, later shifts would need to take 5 degrees off the highs south of Point Conception. The smoke still looks rather dense north of Point Conception and temperatures have been lowered accordingly. Depending on the smoke conditions for Sunday, temperatures should warm up with enough smoke dispersal, or temperatures may need to be scaled back if the thick smoke persists. Aside from challenges created by the smoke, 500 mb heights do not change much in the short term. There is a faint hint in the cross sections that the marine layer depth will slowly increase through the weekend, but patchy dense fog is still a threat through Saturday morning. The pressure gradients do increase for more onshore flow each day into Monday. .LONG TERM (TUE-FRI)...11/250 PM. By Tuesday, the pressure gradients trend weakly offshore for some slight warming of high temperatures Tuesday and Wednesday. The ridge slowly weakens on Wednesday. By Thursday into Friday, an upper low and associated trough push into the west coast and northern and central California. This will decrease heights aloft and increase the onshore flow for cooling temperatures. && .AVIATION...12/0142Z. At 00Z, the marine layer depth was around 400 feet deep at KLAX. The top of the inversion was around 1700 feet with a temperature near 26 degrees Celsius. Low to moderate confidence in the current forecast. Higher confidence in coastal stratus forecast, less confidence in visibility due to smoke. IFR to MVFR conditions in smoke are possible at all terminals through Saturday afternoon. LIFR to IFR conditions are likely for coastal terminals, spreading in through 13Z. VFR conditions should develop at most terminals around 20Z, likely delayed due to smoke. KLAX...MVFR conditions are likely through at least Saturday afternoon due to combination of haze and smoke. There is a 60 percent chance of LIFR to IFR conditions at KLAX due to stratus between 07Z and 16Z. No wind impacts are expected at this time. KBUR...There is a 50 percent of MVFR conditions in smoke, especially during the late night and morning hours. No wind impacts are expected at this time. && .MARINE...11/120 PM. Outer Waters... Conditions will remain below Small Craft Advisory (SCA) levels through Saturday morning. There is a forty percent chance of SCA level wind in the northern and central outer waters Saturday evening through Sunday afternoon, then a seventy percent chance of SCA level gusty wind Sunday evening through mid week for all of the outer waters. Inner Waters... Conditions will remain below SCA level across the inner waters through the forecast period. There will be locally dense fog with poor visibility over the coastal waters through midday today and again overnight tonight through midday Saturday. && .LOX WATCHES/WARNINGS/ADVISORIES... CA...NONE. PZ...NONE. && .HAZARD POTENTIAL OUTLOOK (MON-FRI). No significant hazards expected. && $$ PUBLIC...Sweet AVIATION...Hall MARINE...Kj SYNOPSIS...DB
Area Forecast Discussion...Updated
National Weather Service Saint Louis MO
903 PM CDT Fri Sep 11 2020 .UPDATE... Issued at 857 PM CDT Fri Sep 11 2020 Previous forecast remains on track for overnight tonight. The expectation is for moderate to heavy rainfall rates to become more prevalent as low-level moisture convergence increases along the Mississippi River north of St. Louis. Believe the 0Z RAP is on the right track, which paints the heaviest rainfall totals overnight in far west-central Illinois. The concern remains for training showers and embedded thunderstorms to potentially cause flash flooding. The environment is primed for very efficient rainfall rates due to near-record precipitable water values and very deep warm cloud depths (13-14 kft). Dry antecedent conditions and weak instability are certainly helpful, but the aforementioned environment may overcome these mitigating factors, at least in some isolated areas. Ongoing flash flood watch looks on track, so no changes were made this evening. Gosselin && .SHORT TERM... (Through Late Saturday Afternoon) Issued at 325 PM CDT Fri Sep 11 2020 The stationary front which has been hanging over Missouri for the past few days has finally begun moving northward as a warm front. the low level wave that is causing the front to drift north is a reflection of the upper level low which moved from the Four Corners Region into the Great Plains today. The low will drift slowly east into the Upper Midwest over the next 24 hours and this slow movement will dictate the speed of the cold front which is behind the wave as it moves through Missouri and Illinois. Current indications are that the cold front will not clear the eastern portions of our area in south central Illinois until Saturday night. In the mean time, deterministic guidance shows moderate to strong low level moisture convergence developing this evening and continuing into Saturday morning along a pre-frontal trough which stretches from central into northeast Missouri and west central Illinois. As with the front, this trough will move very slowly to the east through Saturday, and the moisture convergence along is very persistent. P-wats in excess of 2 inches are are indicated on all deterministic models coinciding with this moisture convergence. NAEFS and EC ensembles are also showing P-wats in the 97th to 99th climatological percentiles. Additionally, forecast soundings at UIN have warm cloud depths in excess of 12,000 feet, very conducive to warm rain processes. With all this in mind, have issued a flash flood watch for parts of central and eastern Missouri as well as west central Illinois for tonight into Saturday morning. 2-4 inches of rain look likely with locally higher amounts. The pre-frontal trough moves into east central and southwest Illinois Saturday morning and southeast Missouri during the afternoon, but the moisture convergence along it is not as strong, nor as persistent. That being said, P-wats ahead of the trough are still over 2 inches, so while flash flooding doesn`t look as likely, some locally heavy rainfall is possible. Carney .LONG TERM... (Saturday Night through Next Friday) Issued at 325 PM CDT Fri Sep 11 2020 The cold front finally drifts through the forecast area on Saturday night, with high pressure dropping in behind it. The airmass associated with this high isn`t particularly cold, but it is drier, and guidance is showing dew point temperatures in the low to mid 60s on Sunday vs the low to mid 70s ahead of the front on Saturday. The dry airmass will be with us at least through Tuesday as the high drifts from the Midwest to the Atlantic coast. Mass fields in the medium range deterministic models begin to diverge pretty sharply on Wednesday and look very different from each other for the latter half of the week. The ECMWF has been the most consistent with warmer and more humid conditions building into Missouri and Illinois on Wednesday, while an upper level low moves over the Hudson Bay. The low carves out a deep long wave trough over the eastern U.S. and pushes a strong cold front through the mid Mississippi Valley Thursday night into Friday. The past several runs of the GFS have not agreed with this at all and have not developed that long wave trough over the eastern U.S. and have instead kept the mid Mississippi Valley in weak west-northwest flow aloft with generally quiet weather for the end of the week. This morning`s 12Z run of the GFS decided to come more in line with the EC, but it`s much faster with the upper low and trough, and this pushes the cold front through the mid Mississippi Valley late Wednesday! High pressure would then build into the Midwest and move across the Great Lakes through Friday. I have little faith in the GFS solution at this have a little closer to the EC and the ensemble forecasts. This keeps warmer temperatures and more humid air over the area with a chance for convection each day Wednesday through Friday. Carney && .AVIATION... (For the 00z TAFs through 00z Saturday Evening) Issued at 635 PM CDT Fri Sep 11 2020 The main concerns through Saturday morning will be on low ceilings and reduced visibilities, mainly due to moderate to potentially heavy rainfall. The focus tonight will be along/just behind a slow-moving front, which puts central Missouri northeastward into west-central Illinois as the region of interest. This includes KCOU and KUIN, where rainfall should become more widespread late this evening. In addition, ceilings should lower to IFR, with visibilities in the heavier rain showers below 3SM. Further east, the metro terminals likely will be VFR/dry most of the night. Rain chances increase more toward dawn on Saturday, but rain activity should be more brief and not expecting the heavier downpours either. Behind the front, a period of IFR or low MVFR ceilings are expected for the metro terminals Saturday morning. By afternoon, any rain threat should shift east of the area with low stratus slowly lifting and then scattering out. Dry/VFR conditions favored areawide as a result for Saturday afternoon. SPECIFICS FOR KSTL: Dry/VFR conditions are favored through tonight. Will have to keep an eye on activity not too far west, but current thinking is that it will remain west of the terminal. Chances of rain along a slow-moving cold front increase early Saturday morning. Also cannot rule out a few rumbles of thunder. Behind this front, ceilings should drop to around 900 feet AGL. Conditions then should slowly improve late morning into the afternoon hours as the rain threat shifts east and ceilings lift and then scatter out. Dry/VFR conditions are expected then for Saturday afternoon and evening. Gosselin && .LSX WATCHES/WARNINGS/ADVISORIES... MO...Flash Flood Watch through Saturday morning for Audrain MO-Boone MO-Callaway MO-Knox MO-Lewis MO-Marion MO-Monroe MO- Montgomery MO-Pike MO-Ralls MO-Shelby MO. IL...Flash Flood Watch through Saturday morning for Adams IL-Brown IL- Pike IL. && $$ WFO LSX
Area Forecast Discussion
National Weather Service Pocatello ID
125 PM MDT Fri Sep 11 2020 .SHORT TERM...Tonight through Sunday night. We`re in for a fairly long stretch of warm and dry weather. Satellite imagery shows a significant pool of smoke along the Pacific Coast. HRRR smoke model shows a portion of that migrating through southeast Idaho tonight, but the main area of smoke should stay offshore until Sunday night/Monday as upper flow becomes more southwesterly. Temperatures through the period should be well above normal. Hinsberger .LONG TERM...Monday through next Friday. The upper ridge axis shifts east of region early Monday as energy ejects inland from the trough off the NW coast resulting in a resumption of the SW flow aloft across the region. The GFS is showing a fairly enhanced SW flow with potential Fire Weather implications whereas the ECMWF is a bit more subdued. Either way, we should see a renewed influx of smoke from the California wildfires at that time. The flow relaxes some as the ridge expands further north across the region Tuesday as the low regathers itself off the Oregon/Washington coast. By Wednesday, the GFS and ECMWF solutions diverge once again. Here, the GFS favors the low gradually moving inland Wednesday into Friday with increasing SSW flow aloft across the region Wednesday and Thursday followed by an influx of moisture and instability showers and thunderstorms Friday as the low shifts across Oregon. The 00z ECMWF on the other hand favors a northern branch trough sweeping south through WRN Canada and east along the Canadian highline Wednesday and Thursday with a "clipper" like system generating some showers across the CNTRL mountains and Montana divide as the main low remains anchored off the NW coast through Friday. Thus model uncertainty reigns over the latter half of the week and we will allow the National Blend of Models to work its magic here. Huston && .AVIATION...VFR-SKC conditions with continue through Saturday. Huston && .FIRE WEATHER...Forecast continues to be dry through the period with high pressure remaining in control. We continue to see Haines index of 5 and 6 widespread across southeast Idaho through Sunday night. A slight uptick in winds is expected Monday and Tuesday which, combined with low RH, takes us close to critical fire conditions on those days. Hinsberger && .PIH WATCHES/WARNINGS/ADVISORIES...None. && $$
Area Forecast Discussion
National Weather Service Portland OR
627 PM PDT Fri Sep 11 2020 .SYNOPSIS...Onshore flow continues through the weekend. Some marine air seeps inland to gradually removing some of the entrenched smoke. A trough of low pressure early next week returns chances for showers to the region. && .UPDATE...Surface observations and web cameras show the smoke is especially dense across Lane County from the Cascades to the coast with visibilities at or less than a quarter of a mile. The smoke is also dense in part of the central Oregon coast range and across the north Oregon Cascades. Visibilities of a quarter of a mile or less have the potential to result in traffic delays and collisions providing a new hazard to this smoke besides the ongoing poor air quality. Have therefore issued a dense smoke advisory for the areas mentioned above. Weather models do not handle smoke well, and do not pick up on the impacts smoke has on modeled temperatures. We tend to have to cut day time temperature forecasts 10 degrees or more from what models forecast when observed smoke is opaque enough to block solar radiation. Since the models are warmer for the interior valleys than what we are observing, the pressure in the interior is also too high, as is the onshore pressure gradient. This means that the observed onshore winds are weaker than the model forecasts, and that the dense smoke will likely remain around through Monday. The onshore winds in the hrrr model are stronger than what we are observing, and the hrrr smoke forecast is most likely forecasting relief from the smoke for the coast and coast range too early. The current dense smoke advisory is out through Saturday night, but will likely need to be extended in time or changed in areas throughout the weekend. ~TJ PREVIOUS SHORT TERM...From 248 PM PDT...Tonight through Monday...Dry stable conditions will continue through the weekend as upper level ridging just off the coast slowly shifts east and breaks down. Surface high pressure along the coast is bringing light onshore flow along with shallow marine stratus along the coast. Of course thick widespread smoke across the region is bringing poor air quality. The smoke is keeping the temperatures down and most models are not handling it well. The UW-WRF is much closer to reality with highs inland in the mid 60s to low 70s for the next couple of days. Model soundings continue to forecast a shallow inversion through the weekend. Combined with little surface heating do not expect much in the way of afternoon mixing. Also with the smoke so deep (PIREPs from east and west of the Cascades this morning has FU TOPS FL120) it would only mix more smoke down anyway.In coordination with region air quality agencies an air quality advisory remains in effect through Monday morning. There is some hope for better mixing on Sunday and Monday as the onshore flow increases which may help improve coastal areas. Also with an approaching upper trough the flow turns to the south to southwest we may see some of the smoke pulled offshore. The aforementioned upper trough approaching the region has been advertised by models over the past several days. While the details haven`t been pinned down, the overall message is a pattern shift from upper ridging to southwest flow. This results in more marine influence inland and enough mixing to help stir some of the trapped smoke out of the valley. && .LONG TERM...Monday night through Friday...The extended period is dominated by an cutoff low developing offshore early in the week, which is reasonably agreed upon in the models. Such cutoff lows are traditionally not always well handled by models. Current models have a surface low rotating toward the coast later Mon. This low is tapping into subtropical moisture coming from the western Pacific. 12Z GFS shows PW values near 1.5" to 1-8" just off the coast Mon night. Today`s ECMWF & GEFS IVT values greater than 250kg/m/s is above 80% at our latitude during the same time period. Expect models to vary on the details over the next couple of days, but it looks like some much needed and welcome pcpn is likely later Mon/Tue. For the remainder of next week, the cutoff remains offshore, moving near of 130W later Thu. This sets up more southerly flow over the region which tends to bring a showery unstable pattern. This may bring a slight chance for thunderstorms Wednesday and Thursday over the Cascades. Temperatures through much of the week are likely to remain seasonable. /mh && .AVIATION...00Z TAFS: Current observations across the region are showing visibilities continuing to be at or below 2SM with the smoke registering as a deck around 015 to 025 ft. Winds are light and variable across the region and this trend is expected to continue into tomorrow. Stratus and southerly winds will continue to produce a deck around 003 ft into tomorrow. Expect persistence to be the forecast for the next 24 hours. Refer to for detailed regional aviation weather and hazard information. KPDX and APPROACHES...Smoke will continue to produce IFR to LIFR conditions for the next 24 hours. Light and variable winds will continue to serve as little to no help dissipating the smoke. -BPhillips && .MARINE...Low pressure near 44N, 136W will continue to bring southerly winds across the waters into tomorrow morning. Winds will pick up Saturday afternoon in the outer waters as a weak cold front approaches the coast. Winds will stay below SCA criteria during this time. Seas will remain less than 5 ft as weak swell trains and weak wind waves occupy the waters. There is potential for stronger winds as a more potent front moves in Monday into Tuesday. Winds could reach SCA criteria but waves will likely stay at or below 5 ft. Smoke across the waters, particularly the nearshore will reduce visibility less than 1 mile in most areas. -BPhillips && .PQR WATCHES/WARNINGS/ADVISORIES... OR...Dense Smoke Advisory until 11 PM PDT Saturday for Cascade Foothills in Lane County-Cascades in Lane County-Central Coast Range of Western Oregon-Central Oregon Coast- Northern Oregon Cascade Foothills-Northern Oregon Cascades- South Willamette Valley. WA...None. PZ...None. && $$ Interact with us via social media:
Area Forecast Discussion
National Weather Service Reno NV
226 PM PDT Fri Sep 11 2020 .SYNOPSIS... Dense wildfire smoke will bring degraded air quality through the weekend. Light afternoon breezes are expected today and Saturday. Winds will then increase Sunday through much of next week. Some cooling along with a few light showers near the Oregon border are possible by the middle to the end of next week. && .DISCUSSION... The primary weather concern for this weekend is the ongoing air quality and visibility degradation due to smoke. Then, starting late Sunday afternoon, breezy afternoon winds will create fire weather concerns each day Sunday through Wednesday. For discussion of the upcoming elevated fire risk, please see the fire weather section below. Regarding the smoke impacts through Sunday: HRRR smoke computer model indicates light westerly flow will continue to push smoke from the multiple ongoing California wildfires into northeast CA, the Sierra and into western NV. The worst conditions are likely from evening through morning as smoke settles into valleys overnight, with slow improvements each afternoon. A Dense Smoke Advisory is in effect through Sunday morning. Regarding the outlook for the 2nd half of next week: Afternoon breezes may be fairly light Wednesday with ridging and weak southwest flow aloft. Then, the offshore trough moves closer to the coast, possibly bringing an uptick in winds Thursday along with a tightening of Sierra-to-Great Basin thermal gradients and also slight chances of light rain north of Susanville. Forecast confidence in this scenario is increasing -- however, the timing (which day?) and track (how far south?) of this offshore low is still fairly uncertain. JCM && .AVIATION... Smoke will remain an issue this weekend, with the potential for surface visibility to drop into IFR, especially overnight into the morning hours. Slantwise visibility will be quite poor with terrain obscuration also expected due to smoke. Some improvement is possible each afternoon outside of areas immediately downwind of ongoing wildfires, however, skies will certainly not be clear. Winds will generally be light today and Saturday, under 10 kts, with winds picking up late Sunday and then again each afternoon for much of next week. We could see wind gusts reaching 25+ kts each afternoon. JCM && .FIRE WEATHER... Changes made this forecast cycle: *Increased afternoon/evening winds for most of next week. *Increased overnight humidity for mid through late next week. Warm temperatures, dry conditions, and widespread smoke continues for this weekend with poor humidity recoveries overnight. Upper slopes and ridges may only see overnight RH in the teens to mid 20s through Monday morning. Winds are forecast to be on the lighter side for this afternoon and Saturday, mainly from the west...hence the smoke. Having said that, zephyr winds are possible during this time, especially if daytime temperatures warm a bit out in the Basin and Range. Some smoke improvement is expected for our eastern zones in the afternoon hours, so it is possible that a zephyr wind does develop today and Saturday thanks to the temperature gradient. By Sunday, southwest winds increase in the afternoon as the pressure gradient tightens towards the northwest. An enhanced zephyr is likely at this time with gusts reaching up to 25-30 mph for wind prone locations. This, along with humidity at or below 15% across much of the region, could generate some localized areas of critical fire conditions. Best chances would be for the Sierra Front region, eastern portions of Lassen/Plumas counties, and extending into northern Washoe County. Our attention then turns to Monday and Tuesday afternoons as the gradient looks to continue to tighten in response to low pressure off the Pacific Northwest coast and high pressure over the Four Corners. Gusty west-southwest winds are looking more likely during this time accompanied by low humidity. This would lead to more widespread critical fire conditions for the areas previously mentioned, possibly including the southern Sierra Front region. As of now, we have more confidence in Monday than Tuesday, but we will continue to monitor to see if updates are needed. Most of next week does look to remain breezy/gusty during the afternoon and evening hours with relatively low humidity. Models do indicate overnight RH beginning to improve by Wednesday night through the end of next week, but do not let that get your guard down because even with the higher RH, gusty winds will spread fire. -LaGuardia && .REV Watches/Warnings/Advisories... NV...Dense Smoke Advisory until 11 AM PDT Sunday NVZ001>005. CA...Dense Smoke Advisory until 11 AM PDT Sunday CAZ070>073. && $$ For more information from the National Weather Service visit...
Area Forecast Discussion
National Weather Service Seattle WA
812 PM PDT Fri Sep 11 2020 .SYNOPSIS...Smoke from wildfires will remain an issue into the weekend resulting in air quality issues across the whole region. A frontal system for the start of next week looks to bring showers to the area for some much needed rain. && .SHORT TERM /TONIGHT THROUGH MONDAY/...Substantial smoke remains near the surface across the lowlands this evening with cameras suggesting the heaviest concentrations below 4000 to 5000 feet. HRRR smoke model output suggests that thicker smoke aloft will arrive overnight. Unhealthy to locally hazardous air quality conditions will persist into Saturday. Low level onshore flow continues and stratus along the coast will make a steady march inland overnight to reach Puget Sound well before sunrise. It will burn off by midday, but high temperatures on Saturday will drop a few more degrees as marine air and thick smoke holds temperatures in the 60s to lower 70s. Upper ridging continues to weaken on Sunday with low level onshore increasing a notch. Models are still on track to bring some much needed precipitation chances by late Monday into Tuesday as a closed upper low now well offshore of California finally merges with an upper trough moving down the B.C. coast. No forecast updates anticipated this evening. 27 Previous discussion...The main story is the wildfire smoke and air quality issues across the whole region. Given the flow pattern and abundance of smoke, we`ll likely continue to see air quality issues through the weekend, with conditions possibly improving as we move into Monday. Most areas this afternoon are seeing AQI values in the Very Unhealthy to Hazardous range. And the visibility in the smoke has been 3 miles or less with just filtered sunshine. As a result, temps have been trending a good 10 degrees cooler than forecast guidance with most areas in the 60s. We`ll see these conditions continue on Saturday and Sunday. A frontal system will move inland on Monday (mainly Monday afternoon or Monday night) bringing much needed rain to the region. This, along with a stronger air flow pattern and deeper mixing will help clean things out (at least for areas west of the Cascades). So improvements are on the way. 33 .LONG TERM /TUESDAY THROUGH FRIDAY/...Rain lingers as we move into Tuesday under moist, SW flow. An upper low will continue to send showers into western WA Wed-Fri as it slowly moves inland. Chances are low but we may see a few thunderstorms along the Cascade crest during this period. However, wetting rains are expected and the fire weather danger will remain low. Temperature trends remain close to normal with high temps in the 70s. 33 && .FIRE WEATHER...With the return of onshore flow humidities will continue to climb each day and nighttime recovery will be much better than they`ve been over the past few days. For air operations, smoke over the region will present a problem for visibility as well as low marine layer clouds and areas of morning fog. The marine layer will be deeper each day and push into the west slopes of the Cascades over the weekend. The stratus did not make it all the way around the Olympics this morning, but it should over the weekend. Although fuels will remain dry, critical fire weather is not expected as the humidity climbs and precipitation becomes increasingly likely across Western Washington next week as a weather system slowly moves into the Pacific Northwest. Whether precipitation next week is heavy enough to be considered a wetting rain is a little hard to say, but at least temps will be much closer to average and varying degrees of onshore flow will push marine layer moisture into Western Washington. && .AVIATION...Northwesterly flow aloft will transition more west- southwesterly early Saturday morning. Vsbys will remain diminished through Saturday due to smoke. Vsbys of 1 to 3 SM will be common at all TAF locations. Areas of dense smoke are not out of the question. Not much in the way of vsby improvement Saturday afternoon as winds remains rather light. A stronger marine push tonight will push MVFR to IFR stratus into the Puget Sound and inland areas between 06z and 12z. Cigs will slowly scatter out and lift on Saturday by early afternoon. Winds will be light tonight into Saturday with southwesterly winds under 5 knots. JD KSEA...Smoke through Saturday with vsbys ranging from 1 to 3 SM. There is the possibility for areas of dense smoke to develop tonight into Saturday morning as smoke settles and thickens. Cigs will diminish tonight as marine stratus pushes in. MVFR cigs will lower late tonight with IFR possible briefly Saturday morning. Ceilings will be MVFR through much of the morning before some improvement into the early afternoon. Winds will be light southwesterly at 3 to 6 knots. JD && .MARINE...Smoke for poor visibilities over the coastal and inland waters through Saturday. Areas of dense smoke are possible through the afternoon. Onshore flow through the weekend. Small Craft Advisory winds for the central and eastern portions of the Strait of Juan de Fuca this evening. A front will move through the waters Monday night and Tuesday bringing a chance for showers across the area. Offshore, swells will generally remain westerly through midweek at 3 to 4 feet. Pullin/JD && .HYDROLOGY...The daily hydrology discussion has ended until the start of the next rainy season; it will only be updated as needed until then. && .SEW WATCHES/WARNINGS/ADVISORIES... WA...None. PZ...Small Craft Advisory from 8 PM this evening to 2 AM PDT Saturday for Central U.S. Waters Strait Of Juan De Fuca-East Entrance U.S. Waters Strait Of Juan De Fuca. && $$